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1. Field of the Invention
The invention relates to a process and apparatus for treating biogenic residues, including canteen wastes, meat wastes, sewage sludges, and organic industrial wastes.
2. Description of the Related Art
A process and apparatus of the above type are disclosed by DE 44 03 391 A1. According to this reference temperature-pressure hydrolysis (TPH) is carried out in a tubular reactor. To achieve significant throughput, considerable dimensions are required for a reactor of this type. At a feed rate of, for example, 1.7 metric t of biogenic residue/hour, a reactor of this type would have to have a tube length of several thousand meters.
DE 43 33 468 A1 discloses carrying out a temperature-activated liquid phase hydrolysis in a heatable tubular or cascade stirred reactor to treat biogenic residues. The sealing of the stirrer shafts of reactors of this type is a problem during operation, which customarily takes place at high pressure.
It is an object of the present invention to provide a process and an apparatus that eliminates the disadvantages of the prior art. In particular, according to the present invention, simplification of the reactor and increased throughput are to be achieved.
According to the process-side solution of the invention, the temperature-pressure hydrolysis is carried out in a cylindrical reactor in which the residue to be treated flows axially in a first direction in a radially inner cylinder section and flows axially in a second direction in a radially outer section, the second direction being in the opposite direction to the first direction. This makes possible a continuous process procedure having a high throughput. Using the process of the invention, reactors of smaller size can be implemented which are simply constructed and easy to maintain.
Advantageously, the first direction is directed toward an overflow port and the second direction is directed toward a feed port. At the feed port, expediently, a motive jet maintaining the flow in the reactor is generated. The provision of agitators is not necessary in a reactor operating according to the process of the invention. Accordingly, the sealing problems of the prior art that occur when agitators are used can be avoided.
The shell surface of the reactor, which can be constructed as a loop reactor, is advantageously heated. For this purpose a hot medium, in particular oil, can flow around it.
The flow conditions in the reactor can be controlled by a controlling device connected in an axial bypass, in addition to the impulse input of the motive jet. The controlling device can expediently be a pump.
According to the apparatus-side solution of the invention, the temperature-pressure hydrolysis takes place in a cylindrical reactor in which the residue to be treated flows axially in a first direction in a radially inner cylinder section and flows axially in a second direction in a radially outer section. The apparatus of the invention is simply constructed and easy to maintain. It permits a high throughput.
An illustrative example of an apparatus suitable for carrying out the process of the invention is described in more detail below with reference to the single drawing.